Functional Mitral Stenosis in the Setting of Aortic Regurgitation: Myth or Reality?

Functional mitral stenosis may occur when transmitral flow is impaired in the absence of intrinsic mitral valve disease. We report a case of apparent mitral stenosis associated with severe aortic regurgitation and postoperative resolution after aortic valve replacement. A 54-year-old man with hypertension presented with persistent palpitations and New York Heart Association class III dyspnoea. Electrocardiography showed atrial fibrillation with a mean ventricular rate of 120 beats/min. Transthoracic echocardiography demonstrated severe eccentric aortic regurgitation directed towards the anterior mitral leaflet, with a vena contracta of 6.6 mm, pressure half-time of 210 ms, effective regurgitant orifice area of 34 mm², and regurgitant volume of 70 mL. The anterior mitral leaflet showed fluttering and reduced diastolic opening, with an interleaflet distance of 11 mm, mitral valve area of 1.6 cm² by planimetry, and a mean transmitral pressure gradient of 18 mmHg, despite the presence of thin, morphologically normal mitral leaflets. After heart rate control and multidisciplinary assessment, the patient underwent surgical aortic valve replacement with a mechanical prosthesis. Three weeks after surgery, echocardiography showed normal prosthetic valve function, disappearance of mitral leaflet fluttering, an increase in the intervalvular distance to 26 mm, and normalisation of the mean transmitral pressure gradient to 1.5 mmHg. This case supports the diagnosis of reversible functional mitral stenosis caused by haemodynamic interaction between severe aortic regurgitation and mitral valve motion.